"Where Are They?"

When Enrico Fermi asked his famous question (now known as the Fermi Paradox) more than fifty years ago — if there is advanced extraterrestrial life, intelligence, and technology, why don't we see unmistakable evidence of it? — it was the era of 60-megaton atmospheric bomb tests and broadcast television, with unlimited fusion power in plain sight.

Now, we don't even have underground testing, TV has gone cable, wireless is going spread-spectrum, technology has grown microscopic, our children encrypt text with PGP and swap audio via MP3, and Wolfman Jack no longer broadcasts across the New Mexico desert at 50,000 watts.

Fermi's question is still worth asking — and may not be the paradox we once thought.

George Dyson is a historian among futurists and the author of Darwin Among the Machines.